Ignore TransitEncryptionEnabled in modify when unchanged

If the `TransitEncryptionEnabled` value is unchanged, but added to a
ModifyReplicationGroup call, the ElastiCache API will return an
errorMessage saying:

> Modification of transit encryption is not supported for access control
> enabled clusters.

This is "fixed" by not setting it, or setting it to nil.

Fixes #2536

Author: Gereon Frey

apis/v1alpha1/ack-generate-metadata.yaml

@@ -1,8 +1,8 @@
 ack_generate_info:
-  build_date: "2025-06-11T00:03:37Z"
-  build_hash: e675923dfc54d8b6e09730098c3e3e1056d3c1e9
-  go_version: go1.24.3
-  version: v0.48.0
+  build_date: "2025-06-24T10:48:48Z"
+  build_hash: a488d4e8a9222ed51e5690cb5850beb21cce5a1f
+  go_version: go1.24.2
+  version: v0.48.0-1-ga488d4e
 api_directory_checksum: e7d8480a655968a4f441db9509fd5561aa5eb1c4
 api_version: v1alpha1
 aws_sdk_go_version: v1.32.6

pkg/resource/replication_group/sdk.go

@@ -1,6 +1,9 @@
 	if !delta.DifferentAt("Spec.LogDeliveryConfigurations") {
 		input.LogDeliveryConfigurations = nil
 	}
+	if !delta.DifferentAt("Spec.TransitEncryptionEnabled") {
+		input.TransitEncryptionEnabled = nil
+	}
 	if delta.DifferentAt("UserGroupIDs") {
 		for _, diff := range delta.Differences {
 			if diff.Path.Contains("UserGroupIDs") {
@@ -54,4 +57,4 @@
 				}
 			}
 		}
-	}
+	}